1. Field of the Invention
This invention relates to intravascular devices for implantation within a vessel of the body, and more particularly to a stent device which may be used in the treatment of blood vessel disorders. More specifically, the stent device may take the form of an aneurysm cover to be used in the treatment of aneurysms which occur within the brain.
2. Description of the Prior Art
On a worldwide basis, nearly one million balloon angioplasties are performed annually to treat vascular disease, including blood vessels clogged or narrowed by a lesion or stenosis. The objective of this procedure is to increase the inner diameter or cross-sectional area of the vessel passage, or lumen, through which blood flows. Another serious vascular defect is an area of weakened vessel wall that causes a bulge, or bubble, to protrude out in a radial direction from the vessel. This type of defect is called an aneurysm. If untreated, the aneurysm may continue expanding until it bursts thereby causing hemorrhaging from the vessel.
In an effort to prevent restenosis or to treat an aneurysm without requiring surgery, short flexible cylinders or scaffolds, made of metal or polymers, are often placed into a vessel to maintain or improve blood flow. Referred to as stents, various types of these devices are widely used for reinforcing diseased blood vessels, for opening occluded blood vessels, or to serve as an aneurysm cover to cover the neck of an aneurysm and relieve the pressure within the aneurysm. Some stents are expanded to the proper size by inflating a balloon catheter, referred to as “balloon expandable” stents, while others are designed to elastically expand in a self-expanding manner.
Balloon expandable stents and self-expanding stents are crimped to a small diameter and delivered within a blood vessel using a catheter-based delivery system. When positioned at a desired site within a vessel, these devices are expanded by a balloon, or allowed to self-expand, to the desired diameter. In order to serve as an aneurysm cover, the stent is expanded at a location within the blood vessel adjacent the aneurysm to thereby provide a skeletal cover across the neck of the aneurysm.
One such stent, or aneurysm cover, for the treatment of abdominal aortic aneurysms, is disclosed in U.S. Pat. No. 6,267,783, entitled “Stent Which is Easily Recaptured and Repositioned Within the Body.” This patent discloses a self-expanding stent which may be used in the treatment of aortic aneurysms. This device may be easily recaptured after placement and repositioned to a new position within the vessel.
Another stent device used for the treatment of aneurysms is disclosed in U.S. Pat. No. 6,361,558 to Grant Hieshima, et al., entitled “Stent Aneurysm Treatment System and Method.” This patent discloses vasculature stents of various configurations which may be used as aneurysm covers for occluding, or partially occluding, aneurysms located at various positions along the blood vessels.